Add keyframes to animation framework.

Change-Id: I5c8c8037aeeedae1ce7a18200986caf57264772f

1 files changed, 185 insertions, 0 deletions

diff --git a/core/java/android/animation/Keyframe.java b/core/java/android/animation/Keyframe.java
new file mode 100644
index 000000000000..b98994a37440
--- /dev/null
+++ b/core/java/android/animation/Keyframe.java
@@ -0,0 +1,185 @@
+/*
+ * Copyright (C) 2010 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.animation;
+
+import android.view.animation.Interpolator;
+
+/**
+ * This class represents timea time/value pair for an animation. The Keyframe class is used
+ * by {@link Animator} to define the values that the animation target will have over the course
+ * of the animation. As the time proceeds from one keyframe to the other, the value of the
+ * target object will animate between the value at the previous keyframe and the value at the
+ * next keyframe. Each keyframe also holds an option {@link android.view.animation.Interpolator}
+ * object, which defines the time interpolation over the intervalue preceding the keyframe.
+ */
+public class Keyframe {
+    /**
+     * The time at which mValue will hold true.
+     */
+    private float mFraction;
+
+    /**
+     * The value of the animation at the time mFraction.
+     */
+    private Object mValue;
+
+    /**
+     * The type of the value in this Keyframe. This type is determined at construction time,
+     * based on the type of the <code>value</code> object passed into the constructor.
+     */
+    private Class mValueType;
+
+    /**
+     * The optional time interpolator for the interval preceding this keyframe. A null interpolator
+     * (the default) results in linear interpolation over the interval.
+     */
+    private Interpolator mInterpolator = null;
+
+    /**
+     * Private constructor, called from the public constructors with the additional
+     * <code>valueType</code> parameter.
+     *
+     * @param fraction The time, expressed as a value between 0 and 1, representing the fraction
+     * of time elapsed of the overall animation duration.
+     * @param value The value that the object will animate to as the animation time approaches
+     * the time in this keyframe, and the the value animated from as the time passes the time in
+     * this keyframe.
+     * @param valueType The type of the <code>value</code> object. This is used by the
+     * {@link #getValue()} functionm, which is queried by {@link Animator} to determine
+     * the type of {@link TypeEvaluator} to use to interpolate between values.
+     */
+    private Keyframe(float fraction, Object value, Class valueType) {
+        mFraction = fraction;
+        mValue = value;
+        mValueType = valueType;
+    }
+
+    /**
+     * Constructs a Keyframe object with the given time and value. The time defines the
+     * time, as a proportion of an overall animation's duration, at which the value will hold true
+     * for the animation. The value for the animation between keyframes will be calculated as
+     * an interpolation between the values at those keyframes.
+     *
+     * @param fraction The time, expressed as a value between 0 and 1, representing the fraction
+     * of time elapsed of the overall animation duration.
+     * @param value The value that the object will animate to as the animation time approaches
+     * the time in this keyframe, and the the value animated from as the time passes the time in
+     * this keyframe.
+     */
+    public Keyframe(float fraction, Object value) {
+        this(fraction, value, Object.class);
+    }
+
+    /**
+     * Constructs a Keyframe object with the given time and integer value. The time defines the
+     * time, as a proportion of an overall animation's duration, at which the value will hold true
+     * for the animation. The value for the animation between keyframes will be calculated as
+     * an interpolation between the values at those keyframes.
+     *
+     * @param fraction The time, expressed as a value between 0 and 1, representing the fraction
+     * of time elapsed of the overall animation duration.
+     * @param value The value that the object will animate to as the animation time approaches
+     * the time in this keyframe, and the the value animated from as the time passes the time in
+     * this keyframe.
+     */
+    public Keyframe(float fraction, int value) {
+        this(fraction, value, int.class);
+    }
+
+    /**
+     * Constructs a Keyframe object with the given time and float value. The time defines the
+     * time, as a proportion of an overall animation's duration, at which the value will hold true
+     * for the animation. The value for the animation between keyframes will be calculated as
+     * an interpolation between the values at those keyframes.
+     *
+     * @param fraction The time, expressed as a value between 0 and 1, representing the fraction
+     * of time elapsed of the overall animation duration.
+     * @param value The value that the object will animate to as the animation time approaches
+     * the time in this keyframe, and the the value animated from as the time passes the time in
+     * this keyframe.
+     */
+    public Keyframe(float fraction, float value) {
+        this(fraction, value, float.class);
+    }
+
+    /**
+     * Constructs a Keyframe object with the given time and double value. The time defines the
+     * time, as a proportion of an overall animation's duration, at which the value will hold true
+     * for the animation. The value for the animation between keyframes will be calculated as
+     * an interpolation between the values at those keyframes.
+     *
+     * @param fraction The time, expressed as a value between 0 and 1, representing the fraction
+     * of time elapsed of the overall animation duration.
+     * @param value The value that the object will animate to as the animation time approaches
+     * the time in this keyframe, and the the value animated from as the time passes the time in
+     * this keyframe.
+     */
+    public Keyframe(float fraction, double value) {
+        this(fraction, value, double.class);
+    }
+
+    /**
+     * Gets the value for this Keyframe.
+     *
+     * @return The value for this Keyframe.
+     */
+    public Object getValue() {
+        return mValue;
+    }
+
+    /**
+     * Gets the time for this keyframe, as a fraction of the overall animation duration.
+     *
+     * @return The time associated with this keyframe, as a fraction of the overall animation
+     * duration. This should be a value between 0 and 1.
+     */
+    public float getFraction() {
+        return mFraction;
+    }
+
+    /**
+     * Gets the optional interpolator for this Keyframe. A value of <code>null</code> indicates
+     * that there is no interpolation, which is the same as linear interpolation.
+     *
+     * @return The optional interpolator for this Keyframe.
+     */
+    public Interpolator getInterpolator() {
+        return mInterpolator;
+    }
+
+    /**
+     * Sets the optional interpolator for this Keyframe. A value of <code>null</code> indicates
+     * that there is no interpolation, which is the same as linear interpolation.
+     *
+     * @return The optional interpolator for this Keyframe.
+     */
+    public void setInterpolator(Interpolator interpolator) {
+        mInterpolator = interpolator;
+    }
+
+    /**
+     * Gets the type of keyframe. This information is used by Animator to determine the type of
+     * {@linke TypeEvaluator} to use when calculating values between keyframes. The type is based
+     * on the type of Keyframe created. For example, {@link IntKeyframe} returns a value of
+     * <code>int.class</code>. This superclass returns a value of <code>Object.class</code>.
+     *
+     * @return The type of the value stored in the Keyframe.
+     */
+    public Class getType() {
+        return mValueType;
+    }
+}